The present invention relates to a cable device with a foldable electrical cable for connecting electrical apparatuses with a power source or for connecting housing parts of electrical apparatuses with one another, such as for example for connecting a keyboard with a housing of a portable computer.
Such cable devices are practically used in all electrical apparatuses. In many cases such apparatuses are not permanently connected with a power source through the cable device, or the individual housing parts of the apparatus must be separated from one another or assembled so that a cable device is not required or required not over the whole length. In such cases there is a problem to store the cable in a maximum simple and space-consuming manner.
For this purpose it is known to insert the cable by rolling in a recess of the housing, such as for example in vacuum cleaners. For rolling of the cable a cable drum must be provided. The cable drum cannot have a small diameter in order to provide winding and therefore leads to a relatively high space consumption.
Further it is known to provide in the apparatus a cable which is wound in a helical manner. Under application of an expansion stress the cable is stretched and in a non-stretched condition it is compressed and can be packed in the recess of the apparatus or in associated package housing. In this solution the helical diameter cannot be too small for obtaining a reliable operation. Therefore, a non-used space remains in the interior of the cylindrical casing formed by the helical configuration.
Finally, it can be recognized from all types of folding or rolling of electrical cable, that the bending stress on the cable must not be high to prevent breakage of the cable or to prevent breakage of metal wires or screen in the individual cables. The cable which is protected with a metal screen cannot be used in condition of frequent intensive bending loads with small bending radius.